Which unit is used to express water flow, commonly abbreviated as cfs?

• A. Meters per second
• B. Gallons per minute
• C. Liters per second
• D. Cubic feet per second

Answer: (D)

Flow rate expresses how much water passes a point per unit time. In US customary units, the unit used to express this discharge is cubic feet per second, abbreviated cfs. That’s why this option is the best answer: it specifically denotes cubic feet per second.

Other units describe similar ideas but in different systems or meanings. meters per second measures speed (how fast the water is moving), not the volume moving per second. Gallons per minute and liters per second are valid flow-rate units, but they use different unit systems and are not abbreviated as cfs.

For quick context, 1 cfs is about 0.0283 cubic meters per second or roughly 448.8 gallons per minute. So a stream at 10 cfs would discharge about 4,488 gallons per minute.